The present invention relates to a refrigerating apparatus with reduced restarting load and more particularly to an improvement in a differential pressure valve which, when a compressor is stopped, is rapidly actuated to block the circuit and thereby prevent condensed coolant from flowing into the evaporator.
Improvement in power efficiency of the refrigerator is achieved by balancing the cooling medium pressure before and after the compressor when the compressor is stopped and by blocking the flow of condensed medium into the evaporator while at the same time keeping the high pressure of the condensed medium in the condensor, in order to reduce the restarting load.
For this purpose, it has been the common practice to provide a solenoid valve between the condensor and the capillary tube, which is operated by the compressor operation signal in such a way that it is opened during operation of the compressor and closed while in halt. With refrigerators which are usually used continuously for many hours, however, it is desirable to eliminate the use of solenoid valve even if the power consumption of the solenoid valve is small. It has often been pointed out that the solenoid valve operation can be noisy depending on the location of the refrigerator.
In recent years, therefore, a technology has been developed that employs a pressure valve in place of the solenoid valve.
FIG. 1 shows an example of the refrigerating apparatus that uses such a differential pressure valve. In this example, a rotary compressor A, a condenser B, a capillary tube C, and an evaporator D are connected in series by a pipe E; a differential pressure valve V1 is installed on the pipe E between the condenser B and the capillary tube C; a check valve V2 is installed between the evaporator D and the rotary compressor A; a pressure introducing tube F1 is connected between the suction side of the rotary compressor A after the check valve V2 and the differential pressure valve V1; and another pressure introducing tube F2 is connected to the outlet of the evaporator D before the check valve V2 and the differential pressure valve V1.
The differential pressure valve V1 has a primary port 2 and a secondary port 3 formed in its body 1. Between these ports is formed a valve seat 4 with which a ball 5 comes into or out of contact. Mounted at the lower part of the valve body 1 is a diaphragm 8 which is supported at its periphery by covers 6 and 7. A pressure chamber is formed in the cover 6 and is communicated with the pressure introducing pipe F1. A valve rod 9 is abutted, through a contact metal 16, against the upper side of the diaphragm 8. A spring 15 is installed between the valve rod 9 and the valve body 1. In the illustrated example, a spring retainer 14 mounted on the top of the valve rod 9 keeps the spring 15 in position and also holds the ball 5. The valve rod 9 passes through a packing housing 11 installed between it and the valve body 1 and is sealed by a seal packing 10. To keep the seal packing 10 in position, a packing retainer is pushed down by a leaf spring 13. The pressure introducing tube F2 is communicated with the pressure chamber in the cover 7 on the upper side of the diaphragm 8. To the primary port 2 is connected a pipe E1 coming from the condenser B; and to the secondary port 3 is connected a pipe E2 leading to the capillary tube C.
In the above construction, while the rotary compressor A is in operation, the pressure before and after the check valve V2 is almost equal and low. These pressures are introduced through the pressure introducing tubes F1 and F2 into each side of the diaphragm 8, and the ball 5 is parted by the spring 15 from the valve seat 4 to allow the coolant to flow into the capillary tube C.
Next, when the rotary compressor A is stopped, the high pressure on the delivery side leaks into the suction side so that the pressure on the suction side increases. However, the pressure leak into the suction side is blocked by the check valve V2, so the increased pressure is introduced through the pressure introducing tube F1 to the lower side of the diaphragm. The high pressure thus introduced pushes up the ball 5 against the low pressure on the upper side of the diaphragm 8 and the spring 15 to cut off the coolant flow to the capillary tube C.
In this construction, however, since the differential pressure valve and the check valve are installed separate, it is necessary to provide two pressure introducing tubes running from points before and after the check valve to the pressure differential valve, thereby complicating the circuit and also the piping work that involves brazing.